Target organ localization of memory CD4(+) T cells in patients with chronic beryllium disease

Beryllium-specific CD4+ T cells induced by chemokine neoantigens perpetuate inflammation

Discovering dominant epitopes for T cells, particularly CD4+ T cells, in human immune-mediated diseases remains a significant challenge. Here, we used bronchoalveolar lavage (BAL) cells from HLA-DP2-expressing patients with chronic beryllium disease (CBD), a debilitating granulomatous lung disorder characterized by accumulations of beryllium-specific (Be-specific) CD4+ T cells in the lung. We discovered lung-resident CD4+ T cells that expressed a disease-specific public CDR3β T cell receptor motif and were specific to Be-modified self-peptides derived from C-C motif ligand 4 (CCL4) and CCL3. HLA-DP2-CCL/Be tetramer staining confirmed that these chemokine-derived peptides represented major antigenic targets in CBD. Furthermore, Be induced CCL3 and CCL4 secretion in the lungs of mice and humans. In a murine model of CBD, the addition of LPS to Be oxide exposure enhanced CCL4 and CCL3 secretion in the lung and significantly increased the number and percentage of CD4+ T cells specific for the HLA-DP2-CCL/Be epitope. Thus, we demonstrate a direct link between Be-induced innate production of chemokines and the development of a robust adaptive immune response to those same chemokines presented as Be-modified self-peptides, creating a cycle of innate and adaptive immune activation.

Adaptive Immunity in Pulmonary Sarcoidosis and Chronic Beryllium Disease

Pulmonary sarcoidosis and chronic beryllium disease (CBD) are inflammatory granulomatous lung diseases defined by the presence of non-caseating granulomas in the lung. CBD results from beryllium exposure in the workplace, while the cause of sarcoidosis remains unknown. CBD and sarcoidosis are both immune-mediated diseases that involve Th1-polarized inflammation in the lung. Beryllium exposure induces trafficking of dendritic cells to the lung in a mechanism dependent on MyD88 and IL-1α. B cells are also recruited to the lung in a MyD88 dependent manner after beryllium exposure in order to protect the lung from beryllium-induced injury. Similar to most immune-mediated diseases, disease susceptibility in CBD and sarcoidosis is driven by the expression of certain MHCII molecules, primarily HLA-DPB1 in CBD and several HLA-DRB1 alleles in sarcoidosis. One of the defining features of both CBD and sarcoidosis is an infiltration of activated CD4+ T cells in the lung. CD4+ T cells in the bronchoalveolar lavage (BAL) of CBD and sarcoidosis patients are highly Th1 polarized, and there is a significant increase in inflammatory Th1 cytokines present in the BAL fluid. In sarcoidosis, there is also a significant population of Th17 cells in the lungs that is not present in CBD. Due to persistent antigen exposure and chronic inflammation in the lung, these activated CD4+ T cells often display either an exhausted or anergic phenotype. Evidence suggests that these T cells are responding to common antigens in the lung. In CBD there is an expansion of beryllium-responsive TRBV5.1+ TCRs expressed on pathogenic CD4+ T cells derived from the BAL of CBD patients that react with endogenous human peptides derived from the plexin A protein. In an acute form of sarcoidosis, there are expansions of specific TRAV12-1/TRBV2 T cell receptors expressed on BAL CD4+ T cells, indicating that these T cells are trafficking to and expanding in the lung in response to common antigens. The specificity of these pathogenic CD4+T cells in sarcoidosis are currently unknown.

DNA Methylation Changes in Lung Immune Cells Are Associated with Granulomatous Lung Disease

Epigenetic marks are likely to explain variability of response to antigen in granulomatous lung disease. The objective of this study was to identify DNA methylation and gene expression changes associated with chronic beryllium disease (CBD) and sarcoidosis in lung cells obtained by BAL. BAL cells from CBD (n = 8), beryllium-sensitized (n = 8), sarcoidosis (n = 8), and additional progressive sarcoidosis (n = 9) and remitting (n = 15) sarcoidosis were profiled on the Illumina 450k methylation and Affymetrix/Agilent gene expression microarrays. Statistical analyses were performed to identify DNA methylation and gene expression changes associated with CBD, sarcoidosis, and disease progression in sarcoidosis. DNA methylation array findings were validated by pyrosequencing. We identified 52,860 significant (P < 0.005 and q < 0.05) CpGs associated with CBD; 2,726 CpGs near 1,944 unique genes have greater than 25% methylation change. A total of 69% of differentially methylated genes are significantly (q < 0.05) differentially expressed in CBD, with many canonical inverse relationships of methylation and expression in genes critical to T-helper cell type 1 differentiation, chemokines and their receptors, and other genes involved in immunity. Testing of these CBD-associated CpGs in sarcoidosis reveals that methylation changes only approach significance, but are methylated in the same direction, suggesting similarities between the two diseases with more heterogeneity in sarcoidosis that limits power with the current sample size. Analysis of progressive versus remitting sarcoidosis identified 15,215 CpGs (P < 0.005 and q < 0.05), but only 801 of them have greater than 5% methylation change, demonstrating that DNA methylation marks of disease progression changes are more subtle. Our study highlights the significance of epigenetic marks in lung immune response in granulomatous lung disease.

Immunologic Effects of Beryllium Exposure

Metal-induced hypersensitivity is driven by T-cell sensitization to metal ions. Although numerous metals are associated with the development of diffuse parenchymal lung disease, beryllium-induced hypersensitivity is the best-studied to date. This review focuses on the interaction between innate and adaptive immunity that leads to the development of chronic beryllium disease. After beryllium exposure, activation of the innate immune system occurs through the engagement of pattern-recognition receptors. This activation leads to cell death, release of alarmins, and activation and migration of dendritic cells to lung-draining lymph nodes. These events culminate in the development of an adaptive immune response that is characterized by beryllium-specific, T-helper type 1-polarized, CD4⁺ T-cells and granuloma formation in the lung. The unique ability of beryllium to bind to human leukocyte antigen-DP molecules that express a glutamic acid at position 69 of the β-chain alters the charge and conformation of the human leukocyte antigen-DP-peptide complex. These changes induce post-translational modifications that are recognized as non-self. In essence, the ability of beryllium to create neoantigens underlies the genesis of chronic beryllium disease, and demonstrates the similarity between beryllium-induced hypersensitivity and autoimmunity.

Protective role of B cells in sterile particulate-induced lung injury

Susceptibility to chronic beryllium (Be) disease is linked to HLA-DP molecules possessing a glutamic acid at the 69th position of the β-chain (βGlu69), with the most prevalent βGlu69-containing molecule being HLA-DP2. We have previously shown that HLA-DP2 transgenic (Tg) mice exposed to Be oxide (BeO) develop mononuclear infiltrates in a peribronchovascular distribution and a beryllium-specific, HLA-DP2-restricted CD4+ T cell response. In addition to T cells, B cells constituted a major portion of infiltrated leukocytes in the lung of BeO-exposed HLA-DP2 Tg mice and sequester BeO particles within ectopic lymphoid aggregates and granulomas. B cell depletion was associated with a loss of lymphoid aggregates and granulomas as well as a significant increase in lung injury in BeO-exposed mice. The protective role of B cells was innate in origin, and BeO-induced B cell recruitment to the lung was dependent on MyD88 signaling. Similar to BeO-exposed HLA-DP2 mice, B cells also accumulate in the lungs of CBD subjects, located at the periphery and surrounding the granuloma. Overall, our data suggest a novel modulatory role for B cells in the protection of the lung against sterile particulate exposure, with B cell recruitment to the inflamed lung occurring in an antigen-independent and MyD88-dependent manner.

5-Aminosalicylic Acid Modulates the Immune Response in Chronic Beryllium Disease Subjects

INTRODUCTION

Chronic beryllium disease (CBD) is characterized by accumulation of macrophages and beryllium-specific CD4⁺ T cells that proliferate and produce Th1 cytokines. 5-Amino salicylic acid (5-ASA) is currently used to treat inflammatory bowel disease and has both antioxidant and anti-inflammatory actions. We hypothesized that 5-ASA may be a beneficial therapeutic in CBD.

METHODS

Seventeen CBD patients were randomized 3:1 to receive 5-ASA 500-mg capsules or placebo four times daily for 6 weeks orally. Primary study endpoints included changes in beryllium lymphocyte proliferation (BeLPT). Secondary endpoints included changes in bronchoalveolar lavage (BAL) fluid, cells, serum, and blood cell glutathione (GSH) levels, BAL cell TNF-α levels, lung function, and quality of life measures.

RESULTS

5-ASA decreased BAL cell BeLPT by 20% within the 5-ASA treatment group. No significant changes were observed in serum, PBMCs, BALF, or BAL cell GSH levels in either the 5-ASA or placebo treatment group. 5-ASA treatment decreased ex vivo Be-stimulated BAL cell TNF-α levels within the 5-ASA group and when compared to placebo. Significant improvements were noted in quality of life measurements with 5-ASA treatment.

CONCLUSIONS

5-ASA's ability to decrease BAL cell BeLPT and Be-stimulated BAL cell TNF-α levels suggests that 5-ASA may impact the beryllium-specific immune response in CBD. 5-ASA use in other non-infectious granulomatous lung diseases, such as sarcoidosis, may prove to be a useful alternative treatment to corticosteroids for those with mild to moderate disease.

Beryllium-Induced Hypersensitivity: Genetic Susceptibility and Neoantigen Generation

Chronic beryllium (Be) disease is a granulomatous lung disorder that results from Be exposure in a genetically susceptible host. The disease is characterized by the accumulation of Be-responsive CD4(+) T cells in the lung, and genetic susceptibility is primarily linked to HLA-DPB1 alleles possessing a glutamic acid at position 69 of the β-chain. Recent structural analysis of a Be-specific TCR interacting with a Be-loaded HLA-DP2-peptide complex revealed that Be is coordinated by amino acid residues derived from the HLA-DP2 β-chain and peptide and showed that the TCR does not directly interact with the Be(2+) cation. Rather, the TCR recognizes a modified HLA-DP2-peptide complex with charge and conformational changes. Collectively, these findings provide a structural basis for the development of this occupational lung disease through the ability of Be to induce posttranslational modifications in preexisting HLA-DP2-peptide complexes, resulting in the creation of neoantigens.

Interplay of innate and adaptive immunity in metal-induced hypersensitivity

Metal-induced hypersensitivity is driven by T cell sensitization to metal ions. Recent advances in our understanding of the complex interactions between innate and adaptive immunity have expanded our knowledge of the pathogenesis of these diseases. Metals activate the innate immune system through direct binding to pathogen recognition receptors, activation of the inflammasome, or the induction of cellular death and release of alarmins. Certain metals can serve as adjuvants, promoting dendritic cell activation and migration as well as antigen presentation to metal-specific T cells. These T cells can recognize metals as haptens or as altered MHC-peptide complexes. The ability of metals to create these neoantigens emphasizes the similarity between metal-induced hypersensitivity and autoimmunity.

Beryllium-induced lung disease exhibits expression profiles similar to sarcoidosis

A subset of beryllium-exposed workers develop beryllium sensitisation (BeS) which precedes chronic beryllium disease (CBD). We conducted an in-depth analysis of differentially expressed candidate genes in CBD.We performed Affymetrix GeneChip 1.0 ST array analysis on peripheral blood mononuclear cells (PBMCs) from 10 CBD, 10 BeS and 10 beryllium-exposed, nondiseased controls stimulated with BeSO4 or medium. The differentially expressed genes were validated by high-throughput real-time PCR in this group and in an additional group of cases and nonexposed controls. The functional roles of the top candidate genes in CBD were assessed using a pharmacological inhibitor. CBD gene expression data were compared with whole blood and lung tissue in sarcoidosis from the Gene Expression Omnibus.We confirmed almost 450 genes that were significantly differentially expressed between CBD and controls. The top enrichment of genes was for JAK (Janus kinase)-STAT (signal transducer and activator of transcription) signalling. A JAK2 inhibitor significantly decreased tumour necrosis factor-α and interferon-γ production. Furthermore, we found 287 differentially expressed genes overlapped in CBD/sarcoidosis. The top shared pathways included cytokine-cytokine receptor interactions, and Toll-like receptor, chemokine and JAK-STAT signalling pathways.We show that PBMCs demonstrate differentially expressed gene profiles relevant to the immunnopathogenesis of CBD. CBD and sarcoidosis share similar differential expression of pathogenic genes and pathways.

Metal-specific CD4+ T-cell responses induced by beryllium exposure in HLA-DP2 transgenic mice

Chronic beryllium disease (CBD) is a granulomatous lung disorder that is associated with the accumulation of beryllium (Be)-specific CD4(+) T cells into the lung. Genetic susceptibility is linked to HLA-DPB1 alleles that possess a glutamic acid at position 69 (βGlu69), and HLA-DPB1*02:01 is the most prevalent βGlu69-containing allele. Using HLA-DP2 transgenic (Tg) mice, we developed a model of CBD that replicates the major features of the human disease. Here we characterized the T-cell receptor (TCR) repertoire of Be-responsive CD4(+) T cells derived from the lungs of Be oxide-exposed HLA-DP2 Tg mice. The majority of Be-specific T-cell hybridomas expressed TCR Vβ6, and a subset of these hybridomas expressed identical or nearly identical β-chains that were paired with different α-chains. We delineated mimotopes that bind to HLA-DP2 and form a complex recognized by Be-specific CD4(+) T cells in the absence of Be. These Be-independent peptides possess an arginine at p5 and a tryptophan at p7 that surround the Be-binding site within the HLA-DP2 acidic pocket and likely induce charge and conformational changes that mimic those induced by the Be(2+) cation. Collectively, these data highlight the interplay between peptides and Be in the generation of an adaptive immune response in metal-induced hypersensitivity.

MyD88 dependence of beryllium-induced dendritic cell trafficking and CD4⁺ T-cell priming

Beryllium exposure results in beryllium hypersensitivity in a subset of exposed individuals, leading to granulomatous inflammation and fibrosis in the lung. In addition to its antigenic properties, beryllium has potent adjuvant activity that contributes to sensitization via unknown pathways. Here we show that beryllium induces cellular death and release of interleukin (IL)-1α and DNA into the lung. Release of IL-1α was inflammasome independent and required for beryllium-induced neutrophil recruitment into the lung. Beryllium enhanced classical dendritic cell (cDC) migration from the lung to draining lymph nodes (LNs) in an IL-1R-independent manner, and the accumulation of activated cDCs in the LN was associated with increased priming of CD4(+) T cells. DC migration was reduced in Toll-like receptor 9 knockout (TLR9KO) mice; however, cDCs in the LNs of TLR9-deficient mice were highly activated, suggesting a role for more than one innate receptor in the effects on DCs. The adjuvant effects of beryllium on CD4(+) T-cell priming were similar in wild-type, IL-1R-, caspase-1-, TLR2-, TLR4-, TLR7-, and TLR9-deficient mice. In contrast, DC migration, activation, and the adjuvant effects of beryllium were significantly reduced in myeloid differentiation primary response gene 88 knockout (MyD88KO) mice. Collectively, these data suggest that beryllium exposure results in the release of damage-associated molecular patterns that engage MyD88-dependent receptors to enhance pulmonary DC function.

An official American Thoracic Society statement: diagnosis and management of beryllium sensitivity and chronic beryllium disease

RATIONALE

Beryllium continues to have a wide range of industrial applications. Exposure to beryllium can lead to sensitization (BeS) and chronic beryllium disease (CBD).

OBJECTIVES

The purpose of this statement is to increase awareness and knowledge about beryllium exposure, BeS, and CBD.

METHODS

Evidence was identified by a search of MEDLINE. The committee then summarized the evidence, drew conclusions, and described their approach to diagnosis and management.

MAIN RESULTS

The beryllium lymphocyte proliferation test is the cornerstone of both medical surveillance and the diagnosis of BeS and CBD. A confirmed abnormal beryllium lymphocyte proliferation test without evidence of lung disease is diagnostic of BeS. BeS with evidence of a granulomatous inflammatory response in the lung is diagnostic of CBD. The determinants of progression from BeS to CBD are uncertain, but higher exposures and the presence of a genetic variant in the HLA-DP β chain appear to increase the risk. Periodic evaluation of affected individuals can detect disease progression (from BeS to CBD, or from mild CBD to more severe CBD). Corticosteroid therapy is typically administered when a patient with CBD exhibits evidence of significant lung function abnormality or decline.

CONCLUSIONS

Medical surveillance in workplaces that use beryllium-containing materials can identify individuals with BeS and at-risk groups of workers, which can help prioritize efforts to reduce inhalational and dermal exposures.

p38 Mitogen-Activated Protein Kinase in beryllium-induced dendritic cell activation

Dendritic cells (DC) play a role in the regulation of immune responses to haptens, which in turn impact DC maturation. Whether beryllium (Be) is able to induce DC maturation and if this occurs via the MAPK pathway is not known. Primary monocyte-derived DCs (moDCs) models were generated from Be non-exposed healthy volunteers as a non-sensitized cell model, while PBMCs from BeS (Be sensitized) and CBD (chronic beryllium disease) were used as disease models. The response of these cells to Be was evaluated. The expression of CD40 was increased significantly (p<0.05) on HLA-DP Glu69+ moDCs after 100 μM BeSO₄-stimulation. BeSO₄ induced p38MAPK phosphorylation, while IκB-α was degraded in Be-stimulated moDCs. The p38 MAPK inhibitor SB203580 blocked Be-induced NF-κB activation in moDCs, suggesting that p38MAPK and NF-κB are dependently activated by BeSO₄. Furthermore, in BeS and CBD subjects, SB203580 downregulated Be-stimulated proliferation in a dose-dependent manner, and decreased Be-stimulated TNF-α and IFNγ cytokine production. Taken together, this study suggests that Be-induces non-sensitized Glu69+ DCs maturation, and that p38MAPK signaling is important in the Be-stimulated DCs activation as well as subsequent T cell proliferation and cytokine production in BeS and CBD. In total, the MAPK pathway may serve as a potential therapeutic target for human granulomatous lung diseases.

Molecular mechanisms for contribution of MHC molecules to autoimmune diseases

It will soon be 50 years since the first MHC associations with human disease were described. These seminal studies opened a flourishing area of research, yet much remains to be discovered. Genome-wide association studies of autoimmune diseases have demonstrated that the MHC region has effect sizes that supersede those for any non-MHC locus for most diseases. Thus, an understanding of how particular MHC alleles confer susceptibility will be essential for a comprehensive understanding of autoimmune disease pathogenesis. Here we review recent exciting findings in this important field.

Accelerator mass spectrometry detection of beryllium ions in the antigen processing and presentation pathway

Exposure to small amounts of beryllium (Be) can result in beryllium sensitization and progression to Chronic Beryllium Disease (CBD). In CBD, beryllium is presented to Be-responsive T-cells by professional antigen-presenting cells (APC). This presentation drives T-cell proliferation and pro-inflammatory cytokine (IL-2, TNFα, and IFNγ) production and leads to granuloma formation. The mechanism by which beryllium enters an APC and is processed to become part of the beryllium antigen complex has not yet been elucidated. Developing techniques for beryllium detection with enough sensitivity has presented a barrier to further investigation. The objective of this study was to demonstrate that Accelerator Mass Spectrometry (AMS) is sensitive enough to quantify the amount of beryllium presented by APC to stimulate Be-responsive T-cells. To achieve this goal, APC - which may or may not stimulate Be-responsive T-cells - were cultured with Be-ferritin. Then, by utilizing AMS, the amount of beryllium processed for presentation was determined. Further, IFNγ intracellular cytokine assays were performed to demonstrate that Be-ferritin (at levels used in the experiments) could stimulate Be-responsive T-cells when presented by an APC of the correct HLA type (HLA-DP0201). The results indicated that Be-responsive T-cells expressed IFNγ only when APC with the correct HLA type were able to process Be for presentation. Utilizing AMS, it was determined that APC with HLA-DP0201 had membrane fractions containing 0.17-0.59 ng Be and APC with HLA-DP0401 had membrane fractions bearing 0.40-0.45 ng Be. However, HLA-DP0401 APC had 20-times more Be associated with the whole cells (57.68-61.12 ng) than HLA-DP0201 APC (0.90-3.49 ng). As these findings demonstrate, AMS detection of picogram levels of Be processed by APC is possible. Further, regardless of form, Be requires processing by APC to successfully stimulate Be-responsive T-cells to generate IFNγ.

Identification of multiple public TCR repertoires in chronic beryllium disease

Chronic beryllium disease (CBD) is a granulomatous lung disease characterized by the accumulation of beryllium (Be)-specific CD4(+) T cells in bronchoalveolar lavage. These expanded CD4(+) T cells are composed of oligoclonal T cell subsets, suggesting their recruitment to the lung in response to conventional Ag. In the current study, we noted that all bronchoalveolar lavage-derived T cell lines from HLA-DP2-expressing CBD patients contained an expansion of Be-responsive Vβ5.1(+) CD4(+) T cells. Using Be-loaded HLA-DP2-peptide tetramers, the majority of tetramer-binding T cells also expressed Vβ5.1 with a highly conserved CDR3β motif. Interestingly, Be-specific, Vβ5.1-expressing CD4(+) T cells displayed differential HLA-DP2-peptide tetramer staining intensity, and sequence analysis of the distinct tetramer-binding subsets showed that the two populations differed by a single conserved amino acid in the CDR3β motif. TCR Vα-chain analysis of purified Vβ5.1(+) CD4(+) T cells based on differential tetramer-binding intensity showed differing TCR Vα-chain pairing requirements, with the high-affinity population having promiscuous Vα-chain pairing and the low-affinity subset requiring restricted Vα-chain usage. Importantly, disease severity, as measured by loss of lung function, was inversely correlated with the frequency of tetramer-binding CD4(+) T cells in the lung. Our findings suggest the presence of a dominant Be-specific, Vβ5.1-expressing public T cell repertoire in the lungs of HLA-DP2-expressing CBD patients using promiscuous Vα-chain pairing to recognize an identical HLA-DP2-peptide/Be complex. Importantly, the inverse relationship between expansion of CD4(+) T cells expressing these public TCRs and disease severity suggests a pathogenic role for these T cells in CBD.

Biological exposure metrics of beryllium-exposed dental technicians

Beryllium is commonly used in the dental industry. This study investigates the association between particle size and shape in induced sputum (IS) with beryllium exposure and oxidative stress in 83 dental technicians. Particle size and shape were defined by laser and video, whereas beryllium exposure data came from self-reports and beryllium lymphocyte proliferation test (BeLPT) results. Heme oxygenase-1 (HO1) gene expression in IS was evaluated by quantitative polymerase chain reaction. A high content of particles (92%) in IS >5 μ in size is correlated to a positive BeLPT risk (odds ratio [OR] = 3.4, 95% confidence interval [CI]: 0.9-13). Use of masks, hoods, and type of exposure yielded differences in the transparency of IS particles (gray level) and modulate HO1 levels. These results indicate that parameters of size and shape of particles in IS are sensitive to workplace hygiene, affect the level of oxidative stress, and may be potential markers for monitoring hazardous dust exposures.

Syndecan-2 exerts antifibrotic effects by promoting caveolin-1-mediated transforming growth factor-β receptor I internalization and inhibiting transforming growth factor-β1 signaling

RATIONALE

Alveolar transforming growth factor (TGF)-β1 signaling and expression of TGF-β1 target genes are increased in patients with idiopathic pulmonary fibrosis (IPF) and in animal models of pulmonary fibrosis. Internalization and degradation of TGF-β receptor TβRI inhibits TGF-β signaling and could attenuate development of experimental lung fibrosis.

OBJECTIVES

To demonstrate that after experimental lung injury, human syndecan-2 confers antifibrotic effects by inhibiting TGF-β1 signaling in alveolar epithelial cells.

METHODS

Microarray assays were performed to identify genes differentially expressed in alveolar macrophages of patients with IPF versus control subjects. Transgenic mice that constitutively overexpress human syndecan-2 in macrophages were developed to test the antifibrotic properties of syndecan-2. In vitro assays were performed to determine syndecan-2-dependent changes in epithelial cell TGF-β1 signaling, TGF-β1, and TβRI internalization and apoptosis. Wild-type mice were treated with recombinant human syndecan-2 during the fibrotic phase of bleomycin-induced lung injury.

MEASUREMENTS AND MAIN RESULTS

We observed significant increases in alveolar macrophage syndecan-2 levels in patients with IPF. Macrophage-specific overexpression of human syndecan-2 in transgenic mice conferred antifibrotic effects after lung injury by inhibiting TGF-β1 signaling and downstream expression of TGF-β1 target genes, reducing extracellular matrix production and alveolar epithelial cell apoptosis. In vitro, syndecan-2 promoted caveolin-1-dependent internalization of TGF-β1 and TβRI in alveolar epithelial cells, which inhibited TGF-β1 signaling and epithelial cell apoptosis. Therapeutic administration of human syndecan-2 abrogated lung fibrosis in mice.

CONCLUSIONS

Alveolar macrophage syndecan-2 exerts antifibrotic effects by promoting caveolin-1-dependent TGF-β1 and TβRI internalization and inhibiting TGF-β1 signaling in alveolar epithelial cells. Hence, molecules that facilitate TβRI degradation via endocytosis represent potential therapies for pulmonary fibrosis.

Identification of beryllium-dependent peptides recognized by CD4+ T cells in chronic beryllium disease

Identification of peptides that form complexes with beryllium and class II HLA molecules and are recognized by CD4⁺ T cells from patients with chronic beryllium disease.

Chronic beryllium disease (CBD) is a granulomatous disorder characterized by an influx of beryllium (Be)-specific CD4⁺ T cells into the lung. The vast majority of these T cells recognize Be in an HLA-DP–restricted manner, and peptide is required for T cell recognition. However, the peptides that stimulate Be-specific T cells are unknown. Using positional scanning libraries and fibroblasts expressing HLA-DP2, the most prevalent HLA-DP molecule linked to disease, we identified mimotopes and endogenous self-peptides that bind to MHCII and Be, forming a complex recognized by pathogenic CD4⁺ T cells in CBD. These peptides possess aspartic and glutamic acid residues at p4 and p7, respectively, that surround the putative Be-binding site and cooperate with HLA-DP2 in Be coordination. Endogenous plexin A peptides and proteins, which share the core motif and are expressed in lung, also stimulate these TCRs. Be-loaded HLA-DP2–mimotope and HLA-DP2–plexin A4 tetramers detected high frequencies of CD4⁺ T cells specific for these ligands in all HLA-DP2⁺ CBD patients tested. Thus, our findings identify the first ligand for a CD4⁺ T cell involved in metal-induced hypersensitivity and suggest a unique role of these peptides in metal ion coordination and the generation of a common antigen specificity in CBD.

T cell recognition of beryllium

Chronic beryllium disease (CBD) is a granulomatous lung disorder caused by a hypersensitivity to beryllium and characterized by the accumulation of beryllium-specific CD4(+) T cells in the lung. Genetic susceptibility to beryllium-induced disease is strongly associated with HLA-DP alleles possessing a glutamic acid at the 69th position of the β-chain (βGlu69). The structure of HLA-DP2, the most prevalent βGlu69-containing molecule, revealed a unique solvent-exposed acidic pocket that includes βGlu69 and represents the putative beryllium-binding site. The delineation of mimotopes and endogenous self-peptides that complete the αβTCR ligand for beryllium-specific CD4(+) T cells suggests a unique role of these peptides in metal ion coordination and the generation of altered self-peptides, blurring the distinction between hypersensitivity and autoimmunity.

Impaired function of CTLA-4 in the lungs of patients with chronic beryllium disease contributes to persistent inflammation

Chronic beryllium disease (CBD) is an occupational lung disorder characterized by granulomatous inflammation and the accumulation of beryllium-responsive CD4(+) T cells in the lung. These differentiated effector memory T cells secrete IL-2, IFN-γ, and TNF-α upon in vitro activation. Beryllium-responsive CD4(+) T cells in the lung are CD28 independent and have increased expression of the coinhibitory receptor, programmed death 1, resulting in Ag-specific T cells that proliferate poorly yet retain the ability to express Th1-type cytokines. To further investigate the role of coinhibitory receptors in the beryllium-induced immune response, we examined the expression of CTLA-4 in blood and bronchoalveolar lavage cells from subjects with CBD. CTLA-4 expression was elevated on CD4(+) T cells from the lungs of study subjects compared with blood. Furthermore, CTLA-4 expression was greatest in the beryllium-responsive subset of CD4(+) T cells that retained the ability to proliferate and express IL-2. Functional assays show that the induction of CTLA-4 signaling in blood cells inhibited beryllium-induced T cell proliferation while having no effect on the proliferative capacity of beryllium-responsive CD4(+) T cells in the lung. Collectively, our findings suggest a dysfunctional CTLA-4 pathway in the lung and its potential contribution to the persistent inflammatory response that characterizes CBD.

Trace elements and carcinogenicity: a subject in review

Cancer is known to be a multi-step process, which involves different stages including initiation, promotion, progression and metastasis. Chemical carcinogens including most trace elements can change any of these processes to induce their carcinogenic effects. Various studies confirm that cancer arises from the accumulation of irreversible DNA damage, which results from multiple mutations in critical genes in the body organ. Chemical carcinogens most often directly or after xenobiotic metabolism, act as genotoxic causes to induce DNA damage. Genotoxic carcinogen refers to a group of chemicals capable of producing cancer by directly altering the genetic material of target cells. Other carcinogens are however classified as non-genotoxic, which represents chemicals that are capable of producing cancer by some secondary mechanism not related to direct gene damage. They act as tumor promoters, endocrine-modifiers, receptor mediators, immunosuppressant, or inducers of tissue-specific toxicity and inflammatory responses. The diversity of modes of action, of non-genotoxic carcinogens, the tissue and species specificity and the absence of genotoxicity makes it extremely hard to predict their carcinogenic potential. The roles of trace metals (some of which are either genotoxic or non-genotoxic) in cancer development and inhibition have a complex character and have raised many questions because of their essential and toxic effects on people's health. Trace metals such as cadmium, nickel, arsenic, beryllium and chromium (VI) have been recognized as human or animal carcinogens by International Agency for Research on Cancer (IARC). The Carcinogenic capability of these metals depends mainly on factors such as oxidation states and chemical structures. The oxidative concept in metal carcinogenesis proposes that complexes formed by these metals, in vivo, in the vicinity of DNA, catalyze redox reactions, which in turn oxidize DNA. The most significant effect of reactive oxygen species in the carcinogenesis progression is DNA damage, which results in DNA lesions like strand breaks and the sister-chromatid exchange. This article reviews the carcinogenicity of various trace elements.

Immunotoxicology of beryllium lung disease

Beryllium induces non-caseating granulomatous inflammation in humans exposed to the metal dust or fumes in both occupational and non-occupational settings. The resulting condition, chronic beryllium disease (CBD), affects principally the lungs, lymphatics, and skin and continues to plague modern industry. Beryllium exerts several important immunotoxic effects, including induction of a beryllium-antigen specific adaptive immune response and the triggering of inflammatory and innate immune responses. Genetic susceptibility plays a role in CBD adaptive immune responses, mainly mediated through single nucleotide polymorphisms in HLA-DP and, to a lesser extent, HLA-DR. The adaptive response is characterized by influx and proliferation of CD4+ central and effector memory T cells expressing Th1 cytokines. Insights into the immunopathogenesis of CBD have implications for the understanding of other immune-mediated granulomatous disorders and for metal antigen behavior.

Beryllium-specific CD4+ T cells in blood as a biomarker of disease progression

BACKGROUND

CD4(+) T cells are responsible for the progressive lung damage seen in patients with chronic beryllium disease (CBD), a granulomatous lung disorder in which antigen-specific, T(H)1-type, cytokine-secreting T cells have been characterized. Compared with those seen in beryllium (Be)-sensitized subjects, increased numbers of Be-responsive T cells are present in the blood of patients with CBD.

OBJECTIVE

The aim of this study was to determine whether the number of Be-specific T cells in blood predicted the development of CBD in a cohort of Be-exposed subjects.

METHODS

Using IFN-γ ELISpot and proliferation-based assays, we determined the frequency and proliferative capacity of Be-responsive T cells in blood.

RESULTS

Compared with the Be lymphocyte proliferation test, which detected an abnormal Be-induced proliferative response in 11 (4.2%) of 260 workers from a Be-machining facility, the IFN-γ ELISpot detected a sensitization rate of 10% (χ(2) = 55.7, P < .0001). A significant positive correlation was also noted between the number of Be-responsive CD4(+) T cells in the blood and lung tissue of patients with CBD. Importantly, the transition from Be sensitization to CBD was associated with an increased number of antigen-specific T cells in blood.

CONCLUSION

These findings have important implications for Be-induced disease and potentially other immune-mediated disorders, suggesting that the frequency of antigen-specific T cells in blood can serve as a noninvasive biomarker to predict disease development and severity of the Be-specific CD4(+) T-cell alveolitis.

Mutagenesis of beryllium-specific TCRs suggests an unusual binding topology for antigen recognition

Unconventional Ags, such as metals, stimulate T cells in a very specific manner. To delineate the binding landscape for metal-specific T cell recognition, alanine screens were performed on a set of Be-specific TCRs derived from the lung of a chronic beryllium disease patient. These TCRs are HLA-DP2-restricted and express nearly identical TCR Vβ5.1 chains coupled with different TCR α-chains. Site-specific mutagenesis of all amino acids comprising the CDRs of the TCRA and TCRB genes showed a dominant role for Vβ5.1 residues in Be recognition, with little contribution from the TCR α-chain. Solvent-exposed residues along the α-helices of the HLA-DP2 α- and β-chains were also mutated to alanine. Two β-chain residues, located near the proposed Be binding site of HLA-DP2, played a dominant role in T cell recognition with no contribution from the HLA-DP2 α-chain. These findings suggest that Be-specific T cells recognize Ag using an unconventional binding topology, with the majority of interactions contributed by TCR Vβ5.1 residues and the HLA-DP2 β1-chain. Thus, unusual docking topologies are not exclusively used by autoreactive T cells, but also for the recognition of unconventional metal Ags, such as Be.

Pulmonary fibrosis in response to environmental cues and molecular targets involved in its pathogenesis

Chronic lung injury resulting from a variety of different causes is frequently associated with the develop ment of pulmonary fibrosis in humans. Although the etiology of pulmonary fibrosis is generally unknown, several sources of evidence support the hypothesis that a number of environmental and occupational agents play an etiologic role in the pathogenesis of this disease. The agents discussed in this review include beryllium, nylon flock, textile printing aerosols, polyvinyl chloride and didecyldimethylammonium chloride. The authors also describe a variety of animal models, including genetically modified mice, in order to investigate the molecular mechanism of pulmonary fibrosis, focusing on chemokine receptors, regulatory T cells and transforming growth factor-β and bone morphogenetic protein signaling. Overall, we propose the concept of toxicological pulmonary fibrosis as a lung disease induced in response to environmental cues.

Chronic beryllium disease: an updated model interaction between innate and acquired immunity

During the last decade, there have been concerted efforts to reduce beryllium (Be) exposure in the workplace and thereby reduce potential cases of this occupational lung disorder. Despite these efforts, it is estimated that there are at least one million Be-exposed individuals in the U.S. who are potentially at risk for developing chronic beryllium disease (CBD). Previously, we reviewed the current CBD literature and proposed that CBD represents a model interaction between innate and acquired immunity (Sawyer et al., Int Immunopharmacol 2:249-261, 2002). We closed this review with a section on "future directions" that identified key gaps in our understanding of the pathogenesis of CBD. In the intervening period, progress has been made to fill in some of these gaps, and the current review will provide an update on that progress. Based on recent findings, we provide a new hypothesis to explain how Be drives sustained chronic inflammation and granuloma formation in CBD leading to progressive compromised lung function in CBD patients. This paradigm has direct implications for our understanding of the development of an immune response to Be, but is also likely applicable to other immune-mediated lung diseases of known and unknown etiology.

Linking genetic susceptibility and T cell activation in beryllium-induced disease

Chronic beryllium disease (CBD) is a granulomatous lung disorder caused by beryllium (Be) exposure in the workplace. It is characterized by the accumulation of Be-specific CD4(+) T cells in the lung as well as persistent lung inflammation, culminating in the development of lung fibrosis. CBD occurs in 2 to 16% of Be-exposed workers depending on the individuals' genetic susceptibility and the characteristics of the exposure. Genetic susceptibility to Be-induced disease has been linked to major histocompatibility complex class II molecules. In particular, HLA-DP alleles possessing a glutamic acid at the 69th position of the beta-chain (betaGlu69) are most strongly linked to disease susceptibility. The HLA-DP alleles that present Be to T cells match those implicated in the genetic susceptibility, suggesting that the HLA contribution to disease is based on the ability of those molecules to bind and present Be to T cells. However, the structural features of betaGlu69-containing HLA-DP molecules that explain the disease association remain unknown. We have recently crystallized HLA-DP2, which is the most prevalent of the betaGlu69-containing HLA-DP molecules. Its unique structure, which includes surface exposure of betaGlu69, provides an explanation of the genetic linkage between betaGlu69-containing HLA-DP alleles and Be-induced disease.

Crystal structure of HLA-DP2 and implications for chronic beryllium disease

Chronic beryllium disease (CBD) is a fibrotic lung disorder caused by beryllium (Be) exposure and is characterized by granulomatous inflammation and the accumulation of Be-responsive CD4(+) T cells in the lung. Genetic susceptibility to CBD has been associated with certain alleles of the MHCII molecule HLA-DP, especially HLA-DPB1*0201 and other alleles that contain a glutamic acid residue at position 69 of the beta-chain (betaGlu69). The HLA-DP alleles that can present Be to T cells match those implicated in the genetic susceptibility, suggesting that the HLA contribution to disease is based on the ability of those molecules to bind and present Be to T cells. The structure of HLA-DP2 and its interaction with Be are unknown. Here, we present the HLA-DP2 structure with its antigen-binding groove occupied by a self-peptide derived from the HLA-DR alpha-chain. The most striking feature of the structure is an unusual solvent exposed acidic pocket formed between the peptide backbone and the HLA-DP2 beta-chain alpha-helix and containing three glutamic acids from the beta-chain, including betaGlu69. In the crystal packing, this pocket has been filled with the guanidinium group of an arginine from a neighboring molecule. This positively charged moiety forms an extensive H-bond/salt bridge network with the three glutamic acids, offering a plausible model for how Be-containing complexes might occupy this site. This idea is strengthened by the demonstration that mutation of any of the three glutamic acids in this pocket results in loss of the ability of DP2 to present Be to T cells.

Deficient and dysfunctional regulatory T cells in the lungs of chronic beryllium disease subjects

RATIONALE

Chronic beryllium disease (CBD) is a CD4(+) T cell-mediated disorder characterized by persistent lung inflammation. Naturally occurring regulatory T (T(reg)) cells modulate adaptive immune responses. The role of this T-cell subset in beryllium-induced lung disease is unknown.

OBJECTIVES

The aim of this study was to determine whether dysfunctional T(reg) cells in the lung contribute to the "unchecked" inflammatory response that characterizes CBD.

METHODS

Using blood and bronchoalveolar lavage (BAL) cells from normal control subjects and individuals with beryllium-induced disease, we determined the frequency and function of naturally occurring T(reg) cells.

MEASUREMENTS AND MAIN RESULTS

A significantly decreased percentage and expression of FoxP3 in BAL CD4(+) T cells from CBD patients compared with beryllium-sensitized subjects was seen, and the percentage of FoxP3-expressing CD4(+) T(reg) cells in BAL inversely correlated with disease severity. In contrast to blood T(reg) cells derived from beryllium-sensitized subjects and patients with CBD that completely suppressed blood responder T-cell proliferation, BAL FoxP3-expressing T(reg) cells from patients with CBD are unable to suppress anti-CD3-mediated BAL T-cell proliferation. Mixing studies showed that blood T(reg) cells are capable of suppressing autologous BAL responder T cells. Conversely, BAL CD4(+) T(reg) cells are incapable of suppressing blood T cells, confirming that the failure of BAL T(reg) cells to suppress T-cell proliferation is caused by a dysfunctional T(reg) cell subset and not by resistance of BAL effector T cells to suppression.

CONCLUSIONS

These findings suggest that the deficient and dysfunctional T(reg) cells in the lung of patients with CBD contribute to the persistent inflammatory response in this disease.

The uses and adverse effects of beryllium on health

CONTEXT

This review describes the health effects of beryllium exposure in the workplace and the environment.

AIM

To collate information on the consequences of occupational and environmental exposure to beryllium on physiological function and well being.

MATERIALS AND METHODS

The criteria used in the current review for selecting articles were adopted from proposed criteria in The International Classification of Functioning, Disability, and Health. Articles were classified based on acute and chronic exposure and toxicity of beryllium.

RESULTS

The proportions of utilized and nonutilized articles were tabulated. Years 2001-10 gave the greatest match (45.9%) for methodological parameters, followed by 27.71% for 1991-2000. Years 1971-80 and 1981-90 were not significantly different in the information published and available whereas years 1951-1960 showed a lack of suitable articles. Some articles were published in sources unobtainable through requests at the British Library, and some had no impact factor and were excluded.

CONCLUSION

Beryllium has some useful but undoubtedly harmful effects on health and well-being. Measures need to be taken to prevent hazardous exposure to this element, making its biological monitoring in the workplace essential.

CD27 expression on CD4+ T cells differentiates effector from regulatory T cell subsets in the lung

Beryllium exposure in the workplace can result in chronic beryllium disease, a granulomatous lung disorder characterized by CD4(+) T cell alveolitis and progressive lung fibrosis. A large number of the CD4(+) T cells recruited to the lung in chronic beryllium disease recognize beryllium in an Ag-specific manner and express Th1-type cytokines following T cell activation. Beryllium-responsive CD4(+) T cells in the bronchoalveolar lavage (BAL) express an effector memory T cell phenotype and recognize beryllium in a CD28-independent manner. In this study, we show that the majority of beryllium-responsive CD4(+) T cells in BAL have lost CD27 expression, whereas a subset of beryllium-responsive cells in blood retains expression of this costimulatory molecule. In addition, loss of CD27 on BAL CD4(+) T cells inversely correlates with markers of lung inflammation. A small population of BAL CD4(+) T cells retains CD27 expression, and these CD4(+)CD27(+) T cells contain the FoxP3-expressing, naturally occurring regulatory T (T(reg)) cell subset. Coexpression of CD27 and CD25 identifies the majority of FoxP3-expressing T(reg) cells in blood and BAL, and these cells express potent suppressor function. Taken together, these findings suggest that CD27 is differentially expressed between effector T cells from the inflamed lung and can be used in conjunction with CD25 to isolate T(reg) cells and assess their functional capacity in an ongoing adaptive immune response in a target organ.

Role of high-affinity HLA-DP specific CLIP-derived peptides in beryllium binding to the HLA-DPGlu69 berylliosis-associated molecules and presentation to beryllium-sensitized T cells

Berylliosis is driven by the accumulation in the lung of beryllium-specific T helper type 1 (Th1) cells recognizing beryllium as antigen when presented principally by human leucocyte antigen DP molecules carrying a glutamate at position beta69 (HLA-DPGlu69). This study was designed to clarify the precise role of peptides in beryllium binding to the HLA-DP groove's pocket 4 and to identify peptides with higher affinity for pocket 4 that might prevent beryllium presentation and T-cell stimulation. Beryllium/HLA-DP interactions were analysed by the ability of beryllium to compete with CLIP and CLIP-derived peptides to HLA-DPGlu69 soluble molecule. The CLIP-derived low-affinity peptide CLIP-AA, could not outcompete beryllium; while the CLIP-derived high-affinity peptides CLIP-YY, CLIP-QY and CLIP-RF were only marginally influenced by the presence of beryllium in the competition assay. The effect of these CLIP-derived high-affinity peptides on beryllium presentation was determined by measuring interferon-gamma (IFN-gamma) release upon beryllium stimulation of peripheral blood mononuclear cells obtained from beryllium-hypersensitive subjects. CLIP-YY did inhibit beryllium presentation and T-cell activation, while CLIP-QY and CLIP-RF markedly enhanced the IFN-gamma response to beryllium. Anti-HLA-DP monoclonal antibody blocked the beryllium-induced IFN-gamma release in the presence of CLIP-QY (88%) and CLIP-RF (76%). A similar effect was observed for CLIP-YY capability to block IFN-gamma release by beryllium stimulation in the presence of CLIP-QY (79%) and CLIP-RF (76%). Overall, these data support the proposal that HLA-DP high-affinity peptides might be used as a model for specific berylliosis therapy.

T cell responses to mycobacterial catalase-peroxidase profile a pathogenic antigen in systemic sarcoidosis

Sarcoidosis is a systemic granulomatous disease associated with local epithelioid granulomas, CD4(+) T cells, and Th1 cytokines. The tissue Ags that drive this granulomatous inflammation are uncertain. In this study, we used IFN-gamma-ELISPOT assays and flow cytometry to assess lung and blood T cell responses to the candidate pathogenic Ag, Mycobacterium tuberculosis catalase-peroxidase (mKatG) in patients with sarcoidosis from two centers. Despite differences in patient phenotypic, genetic, and prognostic characteristics, we report that T cell responses to mKatG were remarkably similar in these cohorts, with higher frequencies of mKatG-reactive, IFN-gamma-expressing T cells in the blood of sarcoidosis patients compared with nontuberculosis sensitized healthy controls, and (in a subset) in greater numbers than T cells reactive to purified protein derivative. In sarcoidosis, mKatG-reactive CD4(+) Th1 cells preferentially accumulated in the lung, indicating a compartmentalized response. Patients with or without Löfgren syndrome had similar frequencies of mKatG specific IFN-gamma-expressing blood T cells. Circulating mKatG-reactive T cells were found in chronic active sarcoidosis but not in patients with inactive disease. Together, these results demonstrate that T cell responses to mKatG in sarcoidosis fit a profile expected for a pathogenic Ag, supporting an immunotherapeutic approach to this disease.

4-1BB enhances proliferation of beryllium-specific T cells in the lung of subjects with chronic beryllium disease

In contrast to naive T cells, reactivation of memory cells is less dependent on CD28-mediated costimulation. We have shown that circulating beryllium-specific CD4(+) T cells from chronic beryllium disease patients remain CD28-dependent, while those present in the lung no longer require CD28 for T cell activation. In the present study, we analyzed whether other costimulatory molecules are essential for beryllium-induced T cell function in the lung. Enhanced proliferation of a beryllium-responsive, HLA-DP2-restricted T cell line was seen after the induction of 4-1BB ligand expression on the surface of HLA-DP2-expressing fibroblasts. Following beryllium exposure, CD4(+) T cells from blood and bronchoalveolar lavage of chronic beryllium disease patients up-regulate 4-1BB expression, and the majority of beryllium-responsive, IFN-gamma-producing CD4(+) T cells in blood coexpress CD28 and 4-1BB. Conversely, a significant fraction of IFN-gamma-producing bronchoalveolar lavage (BAL) T cells express 4-1BB in the absence of CD28. In contrast to blood, inhibition of the 4-1BB ligand-4-1BB interaction partially blocked beryllium-induced proliferation of BAL CD4(+) T cells, and a lack of 4-1BB expression on BAL T cells was associated with increased beryllium-induced cell death. Taken together, these findings suggest an important role of 4-1BB in the costimulation of beryllium-responsive CD4(+) T cells in the target organ.

Up-regulation of programmed death-1 expression on beryllium-specific CD4+ T cells in chronic beryllium disease

Chronic beryllium disease (CBD) is caused by workplace exposure to beryllium and is characterized by the accumulation of memory CD4+ T cells in the lung. These cells respond vigorously to beryllium salts in culture by producing proinflammatory Th1-type cytokines. The presence of these inflammatory cytokines leads to the recruitment of alveolar macrophages, alveolitis, and subsequent granuloma development. It has been shown that chronic exposure to conventional Ags leads to up-regulation in the expression of negative regulators of T cells such as programmed death-1 (PD-1). Due to the persistence of beryllium in the lung after the cessation of exposure, aberrant regulation of the PD-1 pathway may play an important role in CBD development. In the present study, PD-1 expression was measured on blood and bronchoalveolar lavage (BAL) CD4+ T cells from beryllium-sensitized and CBD subjects. PD-1 expression was significantly higher on BAL CD4+ T cells compared with those cells in blood, with the highest expression on the beryllium-specific T cell subset. In addition, the expression of PD-1 on BAL CD4+ T cells directly correlated with the severity of the T cell alveolitis. Increased expression of the PD-1 ligands, PD-L1 and PD-L2, on BAL CD14+ cells compared with blood was also seen. The addition of anti-PD-1 ligand mAbs augmented beryllium-induced CD4+ T cell proliferation, and an inverse correlation was seen between PD-1 expression on beryllium-specific CD4+ T cells and beryllium-induced proliferation. Thus, the PD-1 pathway is active in beryllium-induced disease and plays a key role in controlling beryllium-induced T cell proliferation.

Early interstitial lung disease in familial pulmonary fibrosis

RATIONALE

Identification of early, asymptomatic interstitial lung disease (ILD) in populations at risk of developing idiopathic pulmonary fibrosis (IPF) may improve the understanding of the natural history of IPF.

OBJECTIVES

To determine clinical, radiographic, physiologic, and pathologic features of asymptomatic ILD in family members of patients with familial IPF.

METHODS

One hundred sixty-four subjects from 18 kindreds affected with familial IPF were evaluated for ILD. Bronchoalveolar lavage fluid cells were analyzed using flow cytometry. Lung biopsies were performed in six subjects with asymptomatic ILD.

MEASUREMENTS AND MAIN RESULTS

High-resolution computed tomography abnormalities suggesting ILD were identified in 31 (22%) of 143 asymptomatic subjects. Subjects with asymptomatic ILD were significantly younger than subjects with known familial IPF (P < 0.001) and significantly older than related subjects without lung disease (P < 0.001). A history of smoking was identified in 45% of subjects with asymptomatic ILD and in 67% of subjects with familial IPF; these percentages were significantly higher than that of related subjects without lung disease (23%) (P = 0.02 and P < 0.001, respectively). Percentages of activated CD4(+) lymphocytes were significantly higher in bronchoalveolar lavage fluid cells from subjects with asymptomatic ILD compared with related subjects without lung disease (P < 0.001). Lung biopsies performed in subjects with asymptomatic ILD revealed diverse histologic subtypes.

CONCLUSIONS

Asymptomatic ILD in individuals at risk of developing familial IPF can be identified using high-resolution computed tomography scan of the chest, especially in those with a history of smoking. Lung biopsies from individuals in this cohort with early asymptomatic lung disease demonstrate various histologic subtypes of ILD.

Beryllium-induced TNF-alpha production is transcription-dependent in chronic beryllium disease

Beryllium (Be)-antigen presentation to Be-specific CD4(+) T cells from the lungs of patients with chronic beryllium disease (CBD) results in T cell proliferation and TNF-alpha secretion. We tested the hypothesis that Be-induced, CBD bronchoalveolar lavage (BAL) T cell, transcription-dependent, TNF-alpha secretion was accompanied by specific transcription factor upregulation. After 6 h of Be stimulation, CBD BAL cells produced a median of 883 pg/ml TNF-alpha (range, 608-1,275 pg/ml) versus 198 pg/ml (range, 116-245 pg/ml) by unstimulated cells. After 12 h CBD BAL cells produced a median of 2,963 pg/ml (range, 99-9,424 pg/ml) TNF-alpha versus 55 pg/ml (range, 0-454) by unstimulated cells. Using real-time RT-PCR, Be-stimulated TNF-alpha production at 6 h was preceded by a 5-fold increase in TNF-alpha pre-mRNA copy number:beta-actin copy number (Be median ratio 0.21; unstimulated median ratio 0.04). The median ratio of mature TNF-alpha mRNA:beta-actin mRNA was upregulated 1.4-fold (Be median ratio 0.17; unstimulated median ratio 0.12). Be exposure in the presence of the transcription inhibitor pentoxifylline (PTX) decreased CBD BAL cell TNF-alpha pre-mRNA levels > 60%, whereas treatment with the mRNA splicing inhibitor 2-aminopurine (2AP) decreased levels 40% relative to Be exposure alone. PTX treatment decreased mature TNF-alpha mRNA levels 50% while 2AP decreased levels > 80%, relative to Be exposure alone. Beryllium exposure specifically upregulated transcription factors AP-1 and NF-kappaB. The data suggest that Be exposure induces transcription-dependent TNF-alpha production, potentially due to upregulation of specific transcription factors.

Frequency of beryllium-specific, central memory CD4+ T cells in blood determines proliferative response

Beryllium exposure can lead to the development of beryllium-specific CD4+ T cells and chronic beryllium disease (CBD), which is characterized by the presence of lung granulomas and a CD4+ T cell alveolitis. Studies have documented the presence of proliferating and cytokine-secreting CD4+ T cells in blood of CBD patients after beryllium stimulation. However, some patients were noted to have cytokine-secreting CD4 T cells in blood in the absence of beryllium-induced proliferation, and overall, the correlation between the 2 types of responses was poor. We hypothesized that the relative proportion of memory T cell subsets determined antigen-specific proliferation. In most CBD patients, the majority of beryllium-specific CD4+ T cells in blood expressed an effector memory T cell maturation phenotype. However, the ability of blood cells to proliferate in the presence of beryllium strongly correlated with the fraction expressing a central memory T cell phenotype. In addition, we found a direct correlation between the percentage of beryllium-specific CD4+ T(EM) cells in blood and T cell lymphocytosis in the lung. Together, these findings indicate that the functional capability of antigen-specific CD4+ T cells is determined by the relative proportion of memory T cell subsets, which may reflect internal organ involvement.

Identification of HLA-DRPhebeta47 as the susceptibility marker of hypersensitivity to beryllium in individuals lacking the berylliosis-associated supratypic marker HLA-DPGlubeta69

Background

Susceptibility to beryllium (Be)-hypersensitivity (BH) has been associated with HLA-DP alleles carrying a glutamate at position 69 of the HLA-DP β-chain (HLA-DPGlu69) and with several HLA-DP, -DQ and -DR alleles and polymorphisms. However, no genetic associations have been found between BH affected subjects not carrying the HLA-DPGlu69 susceptibility marker.

Methods

In this report, we re-evaluated an already described patient populations after 7 years of follow-up including new 29 identified BH subjects. An overall population 36 berylliosis patients and 38 Be-sensitization without lung granulomas and 86 Be-exposed controls was analysed to assess the role of the individual HLA-class II polymorphisms associated with BH-susceptibility in HLA-DPGlu69 negative subjects by univariate and multivariate analysis.

Results

As previously observed in this population the HLA-DPGlu69 markers was present in higher frequency in berylliosis patients (31 out of 36, 86%) than in Be-sensitized (21 out of 38, 55%, p = 0.008 vs berylliosis) and 41 out of 86 (48%, p < 0.0001 vs berylliosis, p = 0.55 vs Be-sensitized) Be-exposed controls.

However, 22 subjects presenting BH did not carry the HLA-DPGlu69 marker. We thus evaluated the contribution of all the HLA-DR, -DP and -DQ polymorphisms in determining BH susceptibility in this subgroup of HLA-Glu69 subjects. In HLA-DPGlu69-negatives a significant association with BH was found for the HLA-DQLeu26, for the HLA-DRB1 locus residues Ser13, Tyr26, His32, Asn37, Phe47 and Arg74 and for the HLA-DRB3 locus clusterized residues Arg11, Tyr26, Asp28, Leu38, Ser60 and Arg74. HLA-DRPhe47 (OR 2.956, p < 0.05) resulting independently associated with BH. Further, Be-stimulated T-cell proliferation in the HLA-DPGlu69-negative subjects (all carrying HLA-DRPhe47) was inhibited by the anti-HLA-DR antibody (range 70–92% inhibition) significantly more than by the anti-HLA-DP antibody (range: 6–29%; p < 0.02 compared to anti-HLA-DR) while it was not affected by the anti-HLA-DQ antibody.

Conclusion

We conclude that HLA-DPGlu69 is the primary marker of Be-hypersensitivity and HLA-DRPhe47 is associated with BH in Glu69-negative subjects, likely playing a role in Be-presentation and sensitization.

Resident Th1-like effector memory cells in pulmonary recall responses to Mycobacterium tuberculosis

We recently described a model of Th1 recall responses based on segmental antigen challenge with purified protein derivative of Mycobacterium tuberculosis (PPD). Bronchoscopic instillation of 0.5 tuberculin units of PPD resulted in localized lymphocytic inflammation in PPD-positive subjects only. Recruited lymphocytes were predominantly CD4+ and were enriched for cells capable of PPD-specific interferon (IFN)-gamma production. In the current study, we investigated the mechanisms by which this localized recall response is mobilized. Bronchoscopic PPD challenge of skin test-positive subjects resulted in the production of CXCR3 ligands IFN-gamma-inducible protein (IP)-10 and monokine induced by IFN-gamma (Mig), but not of CCR5 ligands macrophage inflammatory protein-1alpha and regulated-upon activation, normal T-cell expressed and secreted, whereas skin test-negative subjects produced none of these chemokines. Baseline bronchoalveolar lavage (BAL) cells of skin test-positive subjects produced IP-10 and Mig in response to in vitro stimulation as well. Because IP-10 and Mig are IFN-gamma-inducible chemokines, these findings suggested that chemokine responses to PPD were facilitated by resident memory cells of the lung. Further studies confirmed that baseline BAL lymphocytes of PPD-positive subjects produce IFN-gamma in response to PPD, and that, compared with peripheral blood, BAL cells are preferentially enriched for PPD-specific lymphocytes. This IFN-gamma production is predominantly a function of CD4+ T cells that display the CD45RO+/CCR7- surface phenotype characteristic of effector memory cells.

Beryllium-Ferritin

A beryllium (Be)-ferritin adduct containing 270 pm of Be stimulated proliferation of bronchoalveolar lavage (BAL) lymphocytes from subjects with chronic beryllium disease (CBD) at concentrations 5-6 logs lower than the amounts of beryllium sulfate (BeSO4) needed to induce proliferation. We observed increased apoptotic CBD BAL macrophages after exposure to both BeSO4 (50 +/- 6%, mean +/- SEM, P <0.05 versus unstimulated controls) and Be-ferritin (40 +/- 2%), whereas only 2.0 +/- 0.2% of BAL lymphocytes underwent activation-induced cell death. Be-ferritin also induced apoptosis in BAL macrophages from subjects with Be sensitization (25 +/- 3%) and in the H36.12j hybrid macrophage cell line (15 +/- 2%). Be-ferritin induced lung macrophage CD95 (Fas) expression and the activation of intracellular caspase-3, -8 and -9. Thus, lung macrophages take up Be-ferritin, delivering physiologically relevant levels of Be that promote Be antigen presentation and macrophage apoptosis. Be-ferritin thereby serves as a "Trojan Horse," triggering proliferation of Be-ferritin-specific CBD BAL T cells. We hypothesize that Be-ferritin exposure may result in persistent antigen exposure inducing Be-specific T cell clonal expansion and T cell helper type 1-type cytokine production and potentially explains the chronicity of CBD and its development years after environmental Be exposure has ceased.

Beryllium-Induced Tumor Necrosis Factor-α Production by CD4+T Cells Is Mediated by HLA-DP

Beryllium (Be) presentation to CD4+ T cells from patients with chronic beryllium disease (CBD) results in T cell activation, and these Be-specific CD4+ T cells undergo clonal proliferation and T-helper 1-type cytokine production. In exposed workers, genetic susceptibility to this granulomatous disorder is associated with particular HLA-DPB1 alleles. We hypothesized that these HLA-DP molecules could mediate Be-stimulated tumor necrosis factor-alpha (TNF-alpha) messenger RNA (mRNA) and protein production. Using intracellular cytokine staining, we found that treatment with an anti-HLA-DP, but not anti-HLA-DR, monoclonal antibody inhibited Be-stimulated TNF-alpha expression in lung CD3+ CD4+ T cells. This monoclonal antibody also blocked Be-specific T cell proliferation, increased production of TNF-alpha mature-mRNA transcripts, and increased TNF-alpha protein production by Be-stimulated CBD peripheral blood mononuclear cells and bronchoalveolar lavage (BAL) cells. The Be-stimulated upregulation of TNF-alpha mature-mRNA levels with TNF-alpha protein production was a unique property of CBD BAL cells, and did not occur in BAL cells from Be-sensitized patients without CBD, or sarcoidosis BAL cells. This study identifies HLA-DP as a regulatory component in the activation of T cell receptors on Be-specific CD4+ T cells from CBD patients resulting in proliferation and proinflammatory cytokine production.

Antigen-specific T cells in rheumatoid arthritis

There is considerable evidence of a key role for CD4+ T cells in the pathogenesis of rheumatoid arthritis. Several attractive candidate antigens, mostly joint-specific, have been studied, but information regarding T cell responses to these antigens in patients is limited and occasionally contradictory. Novel reagents (such as major histocompatibility complex and peptide tetramers) and sensitive techniques (such as intracellular cytokine staining) will aid in future studies to identify antigen-specific T cells. In addition, a new animal model of inflammatory arthritis has recently provided new perspective to the study of rheumatoid arthritis by drawing attention to systemic self-antigens as targets of autoimmunity and anti-self antibodies as markers of T cell activity and effectors of disease.

CD28 costimulation independence of target organ versus circulating memory antigen-specific CD4+ T cells

T cell receptor engagement with CD28 costimulation is generally required for naive T cell activation, whereas reactivation of memory cells is less dependent on CD28 costimulation. We studied this process in chronic beryllium disease, in which the frequency of antigen-specific CD4+ T cells in the lung is large and circulating antigen-specific cells are also detectable. In the lung, a large fraction of CD4+ T cells stopped expressing CD28 mRNA and protein, and this change in phenotype correlated with lung inflammation. In the presence of concentrations of CTLA-4Ig that inhibited the CD28-B7 interaction, beryllium-specific CD4+ T cells in lung were still able to proliferate and secrete IFN-gamma in response to beryllium in culture. This functional independence of CD28 costimulation included lung CD28+ effector cells. Although lung CD4+CD28- cells retained the ability to secrete Th1-type cytokines in response to beryllium, they showed less proliferative capacity and were more susceptible to cell death compared with CD28+ T cells. In contrast to lung cells, inhibition of the CD28-B7 interaction markedly reduced responses of beryllium-specific T cells in blood. Taken together, these findings suggest transition within memory CD4+ T cells from CD28 dependence in central memory cells to functional independence and then loss of CD28 expression in effector cells.